typedef struct mailNode MailNode;

struct mailNode {
  int   msgNum;
  char *from;
  char *to;
  char *subject;
  char *date;
  char *messageId;
  char *inReplyTo;
  enum statusCode status;
  enum priorityCode priority;
  char *content;
  int year, month, day;
  int hour, minute, second;
  MailNode *next;
  MailNode *revNext;
};

int main(int argc, char* argv[])
{
  MailNode *messageList = NULL; // list of messages

  FILE *fp = NULL;
  int i=0;
  char c;
  char command[MAXLLENGTH];  // mail client command

  if (argc != 2) { // Check for correct usage
    fprintf(stderr, "Usage: %s file\n", argv[0]);
    exit(1);
  }

  fp = openMailbox(argv[1]); // open mailbox file


  while (i<7){
  messageList = getNextMessage(fp);
  messageList= messageList->next;   //因为不知道怎么把messList串起来，所以这边做不出来。找了半天找到了很多创建节点的例子，但是找不到怎么把它们串起来的例子，谁能给个例子，谢谢
  i++;
  }

  fclose(fp); // We're done with the mailbox file

  messageList->msgNum = 1;
  //messageList=messageList->revNext;
  printSynopsis( messageList );

  // End of Stage 1

比较简单：

MailNode *temp = NULL;
MailNode *messageList = NULL;

  while (i<7)
{
 if(messageList == NULL)
    messageList=temp=getNextMessage(fp);
 else
{
    temp->next = getNextMessage(fp);
    temp = temp->next;
}
i++;
}
temp = NULL;

messageList就是你需要的链表头，末节点是 NULL。

感谢，感谢。看了你的例子，基本上懂了。